1. Field of the Invention
The present invention relates to a support apparatus for transferring moving loads from one concrete structure to an adjacent concrete structure. The device being particularly relevant for maintaining the spatial relationship between adjoining concrete paving slabs that are spaced apart by a paving joint.
2. Description of the Prior Art
The use of dowel joints to tie adjoining paving slabs is well-known in the art. These dowels are positioned within the concrete formwork, when formwork is used, prior to pouring the concrete so that the dowels extend through the paving joints and are encased in both of the adjoining paving slabs. When slip form paving equipment is being used, the dowels are positioned on the sub grade spaced inwardly from the future longitudinal edge of the slab. The dowels prevent vertical movement between the adjoining slabs at a paving joint so that the load moving from one of the slabs is smoothly transferred to the adjacent slab. There are many different types of concrete paving joints that use load transfer devices. The most prevalent are transverse contraction joints, formed to compensate for the shrinkage that occurs in freshly poured concrete. Other paving joints include transverse and longitudinal expansion joints, transverse and longitudinal construction joints and longitudinal contraction joints.
Various devices exist that support and hold the dowels in the proper position during the pour of the concrete slab. For example U.S. Pat. No. 2,768,562, issued to William S. Godwin discloses a rather complex arrangement of supports that requires a large amount of labor for field assembly, including attachment of the supports to the sides of the forms. The dowels are maintained longitudinally by a pair of baskets that are formed by welding, and then are fitted to a support frame.
In U.S. Pat. No. 5,678,952, issued to Shaw et al., a hollow tube is attached to temperature wire adjacent to the slab formwork. Upon removal of the formwork, a dowel is inserted in the tube so that it extends across the paving joint into the area in which the next slab is to be poured.
In U.S. Pat. No. 3,397,626 issued to J. B. Kornick et al., the dowels extend between loops formed in opposing frames. To hold the dowels firmly in place they are welded to one of the loops. This welding operation must be accomplished at the plant where the wire frames are constructed or must be welded in the field, increasing the costs.
U.S. Pat. No. 6,019,546 issued to Ruiz, discloses a pair of opposing wire supports that have loops and cradles alternately formed therein. To attach the dowels to the wire supports, a key, having a widened center portion, must be inserted between the cradle and the dowel.
Since it is desirable that the dowels be held firmly in place during a concrete pour, many support systems require that the dowels be tack welded to a support frame before it is delivered to the construction site. Such requirements increase the assembly and transportation cost, as the frames with the tack welded dowels attached are bulky and awkward to ship. This method of assembly has reduced the labor in the field but has increased the fabrication and shipping costs. Therefore, what is needed is an apparatus where the dowels may be easily maintained in the proper position with little labor involvement.
It has been pointed out that the prior art is either so complex that it is expensive to make, or it requires welding and thereby increases the labor costs and frequently the transportation costs. Therefore, it remains clear that there is a need for a device to support load transfer dowels that is simple to manufacture, easily stacked for transportation and easily installed in the field, providing a simple and sufficiently tight connection without welding.
The present invention comprises a support apparatus for placing a load transfer dowel within a concrete construction. The present apparatus is inexpensive to manufacture, easy to transport and easy to install in the field. The apparatus is particularly suited for highway construction, and for clarity the discussion in the specification concerning method of use will be directed primarily to highway construction. However, the support apparatus may be used in the assembly of other concrete structures that require dowels or reinforcing bars to join adjacent concrete structures.
There are many different types of concrete paving joints that use load transfer devices. The most prevalent are transverse contraction joints, formed to compensate for the shrinkage that occurs in freshly poured concrete. Other paving joints include transverse and longitudinal expansion joints, transverse and longitudinal construction joints and longitudinal contraction joints.
Most simply stated, the apparatus comprises first and second supports that are positioned on a roadbed subgrade so they are spaced apart from one another and are situated on opposing sides of the concrete paving joint separating the adjacent slabs. One of the supports extends between the planned longitudinal edges of one of the adjoining slabs, and the other support extends between the planned longitudinal edges of the other slab. The first and second supports position the dowels so that when they are inserted within the supports they extend across the paving joint at a predetermined height above the subgrade, at predetermined intervals, and generally parallel to longitudinal edges of the concrete pavement.
Each support comprises at least one member that extends longitudinally the full-length of the support. At least two cross members are attached to the member, with one cross member attached at each location that has been predetermined for placement of a dowel. As there are normally a plurality of dowels to be placed across a paving joint, there are normally a plurality of cross members attached to the member. These cross members are spaced in accordance with the predetermined spacing of the dowels. Each cross member has a first end and a second end and the cross members are attached to the member at a point that is proximal to the first end of each cross member with a predetermined portion of the cross members extending outwardly from the member a predetermined length.
Each support also comprises at least one clip, which is attached to the member. The clip comprises a body which has an opening through its outer surface into a cavity. The opening and the cavity of the body are sized and configured to receive the first end of one of the cross members therein. A gripper is connected to the body so that the gripper can grasp the member, thereby attaching the clip to the member. A cylindrical sleeve, having a closed first end and an open second end, is attached to the body so that a longitudinal axis passing through the sleeve is generally normal to the member. When the first and second supports are positioned on the subgrade, they are spaced apart a predetermined distance from one another and they are aligned so that the longitudinal axes of the opposing sleeves are generally coincident. The first end of a dowel may now be received in one sleeve and the second end of that dowel may be received by the opposing sleeve.
The invention accordingly comprises an article of manufacturer possessing the features, properties, and the relation to elements which will be exemplified in the article hereinafter described, and the scope of the invention will be indicated in the claims.